sullivan algebra and trigonometry: section r.3 geometry review objectives of this section use the...
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Sullivan Algebra and Trigonometry: Section R.3
Geometry Review
Objectives of this Section
• Use the Pythagorean Theorem and Its Converse
• Know Geometry Formulas
A right triangle is on that contains a right angle, that is, an angle of 90°. The side
opposite the right angle is the hypotenuse.
The Pythagorean Theorem
In a right triangle, the square of the length of the hypotenuse is equal to the sum of
the squares of the lengths of the legs.
2 2 2a b c+ =
Example: The Pythagorean Theorem
Show that a triangle whose sides are of lengths 6, 8, and 10 is a right triangle.
We square the length of the sides:
2 2 26 36 8 64 10 100= = =
Notice that the sum of the first two squares (36 and 64) equals the third square (100). Hence the triangle is a right triangle, since it satisfies the Pythagorean Theorem.
Converse of the Pythagorean Theorem
In a triangle, if the square of the length of one side equals the sums of the squares of the lengths of the other two sides, then the triangle is a right triangle. The 90 degree angle is opposite the longest side.
For a rectangle of length L and width W:
2 2Area lw Perimeter l w= = +
For a triangle with base b and altitude (height) h:
Geometry Formulas
1
2Area bh=
For a circle of radius r (diameter d = 2r)2 2Area r Circumference r dp p p= = =
Geometry Formulas
For a rectangular box of length L, width W, and height H:
Volume lwh=
For a sphere of radius r:
3 244
3Volume r Surface Area rp p= =
For a right circular cylinder of height h and radius r:
2Volume r hp=
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